V.F. Červený is credited with inventing the Promovka or Primhorn in F alto in 1867.
This horn was imported by Louis Vitak, sole authorized U.S. agent for V.F.
Červený & Sons, as shown in his 1905 Catalog. It features the patented valve
set with spring tension adjustment thumbscrews.

The horn was probably shipped from the factory without labeling as a stencil horn.
The engraving on the garland was probably added by the importer, Vitak.

1905 Louis Vitak Catalog

(Above) The serial number 20183 is just 3 away from its companion
F/E♭ single horn.
The horn originally came with terminal crooks in F, E♭, D, and C, with the valve
slides graduated for those keys (Left).

The valve set retains the spring tension adjustment thumbscrews
designed by Jaroslav Červený in 1873 but with the rotors mounted vertically in the usual
way instead of horizontally as on earlier Červený models. The number
1438 stamped on the underside of the valve key saddle is apparently a
part number. The same valve set and number appear on the companion
concert horn. This is probably a
result of Červenýs adoption as early as 1843 of American manufacturing methods including
the use of standardized parts.

References

Waterhouse, William, The New Langwill Index of Wind Instrument Makers and Inventors, pub.Tony Bingham, London 1993